Technical Corner

Technical corner

User guide

Getting Started

You just downloaded Linphone on your iPhone, Android or Windows Phone 8. Great ! But what happens now ? What's that complicated settings view?

Let's go to the basics: before being able to place calls to any number worldwide, you need to purchase a SIP account from a VoIP operator or you can use our free SIP service. The VoIP operator's role is to transform a pure internet VoIP call into classical PSTN call, thanks to a set of machines called gateways.

Linphone is a general purpose SIP softphone that isn't bound to any operator. Because it is compatible with SIP, it can work with any VoIP operator using SIP (most of them use SIP, the most notable exception being Skype). Linphone.org is not affiliated nor recommends a VoIP operator in particular. We invite you to select a VoIP provider in your country by browsing the web, and compare rates etc…

Note that you might have a SIP account included with your internet line subscription: it is the case in France for clients of the free.fr internet provider, who is powering the freephonie.net VoIP network.

Ok I have now a SIP account at some-voip-company dot com, what do I do?

Go to the settings page of Linphone. On android it is accessible through the "menu" button, on iPhone the settings are located within the Settings application, together with all other iPhone settings. You'll have to enter at least three things:

Username

Domain

Password

All this information should be provided to you by your VoIP operator during signup process. For your information, username and domain form your SIP identity when grouped together like an email address:sip:my_username@my_voip_provider

Sometimes, VoIP providers might require to setup also the "Proxy" field. This happens when the domain is different from the proxy.

And that's all. Once returned back from the settings page, Linphone should say something like "Registered on XXXX" or "Registration on XXXX successful".

You can now place calls.

All other settings are for advanced users or geeks who want to play with the software.

Learn more

What is SIP ?

SIP is a protocol for establishing Voice over IP calls. It is an open standard, published by the IETF organisation, who made the vast majority of internet protocols. It is inspired from e-mail and http. The following section describes the basic principles of SIP from the user's standpoint, and how to make SIP calls.

Direct SIP calls in local network

Just enter sip:<hostname or IP address> in the SIP url bar of linphone to place a call to another linphone running in your network.

This works also on the public internet provided that the two machines have public IP addresses or appropriate firewall rules.

Internet calls through a SIP proxy

On the public internet, because of dynamic IP addresses, mobility, firewalls, direct calls are not really usable. That's why the concept of SIP proxy exists: the proxy is responsible for routing calls whatever the IP address of end-users is. VoIP operators company are deploying SIP proxies on the internet to get SIP calls routed for their subscribers.

In a first step, the user has to subscribe for the service by choosing a username (sometimes a number) and password. Your public sip identity is then sip:<your username>@<your voip provider>, this is the address that other people can use to reach you using SIP.

Then, by configuring the client (such as Linphone) to go through the proxy, you get a public sip address on the internet, in the same way you have an email address. Other people subscribed to this operator can be reached simply by typing their username or phone number.

The routing of pure internet calls is a service that is often free. Linphone.org is powering a free SIP proxy service, you can register here.

Calls to normal phone numbers

VoIP operators for most of them also provide attractive prices to place VoIP to PSTN (= classical telephony) through their proxies and gateways. You could then call anybody in the world from your favourite linphone client, by simply entering his/her international phone number. The SIP username becomes a phone number.

Choosing a voip operator

The Linphone project is not affiliated with any VoIP or telecom operator, thus we do not recommend or promote any of them in particular. By typing "voip operator" in your favourite search engine you will get hundreds of answers. You can refine the search by country to get more pertinent answers.

Linphone is using the standard and well known SIP protocol. As such, it should be compatible with any voip operator using SIP for its network.

FAQ

What should I put in username and domain in the settings ?

In order to use Linphone to call any number, you need to subscribe a SIP VoIP account to a VoIP operator. Linphone.org does not recommend an operator in particular, however for convenience you can run the wizzard to create a free linphone.org account, which allows you to call friends also registered on linphone.org.

Why H264 and MPEG4 are not available in Android and iOS versions available from Google Play and AppStore ?

H264 and MPEG4 are video encoding formats subjects to patents royalties, thus can hardly be distributed in a free application. We encourage people to move to VP8, which provides quality similar to H264, but is royalty free.H264 and MPEG4 support remains in the source code, so anyone building the Linphone application from source will get them enabled by default.

It works great with wifi but not in 3G ! Why ?

You first need to make sure you are allowed to use VoIP with your 3G connection, check your contract with your mobile operator. Some mobile operators have clauses to forbid VoIP on their network, and they then block all VoIP traffic.Despite technical solutions exist to workaround these limitations, we do not wish to enter such a fight. We aim Linphone to be a software that innovates to solve technical problems, not legal ones.Linphone.org thinks it is not fair to offer such restricted internet access. We hope this is a temporary situation: more and more mobile operators choose to open their 3G network to VoIP.It is likely because your mobile operator is blocking VoIP traffic, because it forbids VoIP in its contracts.

Why aren't you developing a VoIP anti blocage solution ?

Yes VoIP blocage is something that should not exist, that's not real internet. Technically, an anti-blocage solution requires a server infrastructure that linphone.org cannot afford, and we don't want to fight against anybody. Also, there are operators that don't block VoIP in many countries.